<template>
  <div>
    <p>请选择你要购买的书籍</p>
    <ul>
      <li v-for="(item, index) in arr" :key="index">
        {{ item.name }} <button @click="addFn(index)">买书</button>
      </li>
    </ul>

    <table border="1" width="500" cellspacing="0">
      <tr>
        <th>序号</th>
        <th>书名</th>
        <th>单价</th>
        <th>数量</th>
        <th>合计</th>
      </tr>
      <tr v-for="obj,index in arr" :key="index">
          <td>{{index+1}}</td>
          <td>{{obj.name}}</td>
          <td>{{obj.price}}</td>
          <td>{{obj.count}}</td>
          <td>{{obj.price*obj.count}}</td>
      </tr>
    </table>
    <p>总价格为:{{totalFn}}</p>
  </div>
</template>

<script>
export default {
  data() {
    return {
      arr: [
        {
          name: "水浒传",
          price: 107,
          count: 0,
        },
        {
          name: "西游记",
          price: 192,
          count: 0,
        },
        {
          name: "三国演义",
          price: 219,
          count: 0,
        },
        {
          name: "红楼梦",
          price: 178,
          count: 0,
        },
      ],
    };
  },
  methods: {
      addFn(index){
       this.arr[index].count++
      },
     
  },
  computed: {
      totalFn(){
        return  this.arr.reduce((sum,obj)=>{
             sum+= obj.price*obj.count
             return  sum
         },0)
     }
  }
};
</script>